Control means for recording device

ABSTRACT

A control means for controlling the operation of a recording device having a plurality of modes of operation in response to a plurality of control currents. The control means provides for control of the recording device from one or more operating stations and the control means includes a plurality of current means for providing a plurality of control currents in response to a plurality of potential differences between a plurality of first voltages provided by a circuit means and a variable second voltage provided by a selecting means. The variable second voltage is selectively varied at the recording device from an operating station with substantially no flow of current between the recording device and the operating station and with a minimum number of wires required between the recording device and the operating station. Thus, the control means is reliable because it is independent of fluctuations of current between a recording device and an operating station and is relatively inexpensive because of the small number of wires required between a recording device and an operating station.

United States Patent [72] lnventors Fred C. Bolick, Jr.;

James B. Godwin, Atlanta, Ga.

[21] Appl. No. 727,877

[22] Filed Mar. 9, 1968 [45] Patented Mar. 9, 1971 [73] Assignee LanierElectronic Laboratory Incorporated Atlanta, Ga.

[54] CONTROL MEANS FOR RECORDING DEVICE OTHER REFERENCES An electricSelector Switch Employing Transistors by Gerald B. l-lerzog RCATechnical Note 142 (Three Pages Recieved U.S. Patent Office 4/1958)Primary ExaminerDonald D. Forrer Assistant Examiner-Harold A. DixsonAttorney-Jones & Thomas ABSTRACT: A control means for controlling theoperation of a recording device having a plurality of modes of operationin response to a plurality of control currents. The control meansprovides for control of the recording device from one or more operatingstations and the control "means includes a plurality of current meansfor providing aplurality of control currents in response to a pluralityof potential differences between a plurality of first voltages providedby a circuit means and a variable second voltage provided by a selectingmeans. The variable second voltage is selectively varied at therecording device from an operating station with substantially no flow ofcurrent between the recording device and the operating station and witha minimum number of wires required between the recording device and theoperating station. Thus, the control means is reliable because it isindependent of fluctuations I of current between a recording device andan operating station and is relatively inexpensive because of the smallnumber of wires required between a recording device and an operatingstation.

PATENTED HAR 91971 BY James B. Godwin.

ATTORNEXS coNrnoi. MDANs son nnconnmo DEVICE BACKGROUND or THE INVENTIONl Field of the invention This invention relates to recording devices forrecording on a recording medium using a plurality of modes of operationand more particularly, to a control means for controlling the operationof a recording device from at least one operating station and whichrequires a minimum number of wires between the operating station and therecording device and substantially no flow of current between theoperating station and the recording device.

2. Description of the Prior Art A recording device for recordingmaterial on a recording medium using a plurality of modes of operationof the record ing device which are controlled from an operating stationis well known in the prior art. An essential requirement for such aprior art recording device is a control means for controlling theoperation of the recording device from an operation station. However,the control means which has generally been used with a prior artrecording device has caused a number of problems. i I

For example, the control means which has generally been used with aprior an recording device has customarily required a relatively largenumber of wires between the recording device and each operating stationin order for the plurality of modes of operation of the recording deviceto be controlled from eaoh operating station. A relatively large numberof wires between a recording device and each operating station not onlymakes the installation of a recording system including the recordingdevice difiicult but also serves to increase the cost of the recordingsystem in proportion to the number of wires required between therecording device and each operating station.

In addition, the control means which has generally been used with at artrecording device has frequently required a relatively large current flowbetween the recording device and each operating station to providecontrol voltages or currents in the prior art recording device. Anexample of such a control means is that used with the recording devicedescribed in U.S. Pat. No. 2,820,852, issued on Jan. 21, 1958, to L. R.Jones et al. for a Dictation System and in this control means and inother control means requiring a relatively large current flow betweenthe recording device and an operating station, the resistance of thewires between the recording device and the operating station and otherfactors .cause reductions or fluctuations in the current which make theoperation of the recording device from an operating station unreliable.

SUMMARY OF THE INVENTION The invention disclosed herein is a controlmeans for controlling the operation of a recording device which avoidsthe foregoing and other problems encountered in the prior art in thatthe invention is a control means which requires that only one or at themost two wires be used between the recording device and an operatingstation and which requires substantially no current flow between therecording device and an operating station. Specifically, the inventionis a control means which includes a plurality of current means forproviding a plurality of control currents that are within and restrictedto the recording device and that are in response to a plurality ofpotential differences between a plurality of different first voltagesand a plurality of different second voltages, circuit means forproviding all of the plurality of different first voltagessimultaneously to the plurality of current means so that the firstvoltage at each of the plurality of current means is different from thefirst voltage at others of the plurality of current means, and selectingmeans for providing the plurality of different second voltagessequentially to the plurality of current means so that the secondvoltage at each of the plurality of current means changes substantiallysimultaneously at all of the piurality of current means.

The changing of 'a second voltage at all of the plurality of currentmeans while the plurality of different first -voltages are beingsimultaneously applied to all of the plurality of current means causes aplurality of potential differences at each of the plurality of currentmeans to which each of the plurality of current means is selectivelyresponsive. As a result, a plurality of control currents are provided bythe plurality of current means in the recording device simply inresponse to changes in a second voltage. it is because the plurality ofcontrol currents provided by the invention are within and restricted tothe recording device and because a second voltage is readily changed ata recording device from an operating station with a minimum number ofwires and substantially no current flow between the recording device andthe operating station that the invention provides a control means forcontrolling a recording device which requires only one or two wiresbetween the recording device and an operating station.

In that embodiment of the invention disclosed herein, each of theplurality of current means includes a first potential responsive elementand a second potential responsive element. The first potentialresponsive element is simply a first transistor having a first voltageapplied to its emitter by the circuit means and a second voltage appliedto its base by the selecting means. The second potential responsiveelement is simply a second transistor having the potential of thecollector of the first transistor applied to its base and asubstantially fixed predetermined control voltage across its emitter andcollector.

Moreover, the circuitmeans and the selecting means are simply voltagedividei' circuits with the voltage division provided by the circuitmeans being substantially constant and with the voltage divisionprovided by the selecting means being readily changed from an operatingstation. Thus, the in-' vention disclosed herein not only provides acontrol means for controlling a recording device with a minimum numberof wires and substantially no current flow between the recording deviceand an operating station, but also a control means which is readilyembodied in an embodiment that is relatively simple in construction soas to be relatively inexpensive to manufacture and easy to maintain.

DESCRIPTION OF THE DRAWING These and other features and advantages ofthe invention will be more clearly understood from the followingdetailed description and the accompanying drawing in which the FIGURE isa schematic presentation of an embodiment of the invention.

DESCRIPTION OF AN EMBODIMENT This FIGURE and the following detaileddescription disclose a specific embodiment of the invention. However, itwill be understood that the invention may be embodied in otherequivalent vention.

The invention disclosed herein may be most easily understood as acontrol means for controlling the operation of a recording devicegenerally designated by the dashed line box 10 in the FIGURE. Usually,the recording device 10 is controlled from an operating stationgenerally designated by the dashed line box 11 in the FIGURE.

Neither the recording device 10 nor the operating station ll is shown ordescribed in detail since those skilled in the art will understand thegeneral arrangement of a recording device 10 having a plurality of modesof operation such as recording, recording-reverse, and recording-review,and of an operating station ll having a plurality of switches which aremanipulated to select the plurality of modes of operation. As a result,the FlGURE shows only the schematic presentation of a control meanswhich is for controlling the operation of the recording device 10 andwhich embodies the invention disclosed herein.

forms without departing from the scope of the insecond voltage dividercircuit 13 includes a resistor R6 selectively in series with a resistorR7, R8, R9, or R between the voltage V1 and ground G. The resistors R7,R3, R9, and R10 are located at the operating station 11 and the placingof these resistors R7, R8, R9, or R10 in series with the resistor R6 isdescribed below.

In parallel between the first voltage divider circuit 12 and the secondvoltage divider circuit 13 are a plurality of PNP junction transistors14, 15, 16, and 17. The emitter E of the transistor 14 is connected tothe first voltage divider circuit 12 between the resistor R1 and theresistor R2 and the emitter E of the transistor is cone connected to'the first voltage divider circuit 12 between the resistor R2 and theresistor R3. Similarly, the emitter E of the transistor 16 is connectedto the first voltage divider circuit 12 between the resistor R3 and theresistor R4 and the emitter E of the transistor 17 is connected to thefirst voltage divider circuit 12 between the resistor R4 and theresistor R5.

The base B of each of the transistors 14, 15, 16, and 17 is connectedthrough one of a plurality of diodes D and a resistor R11, R12, R13, orR14 to the second voltage divider circuit 13 at a point P between theresistor R6 and the resistors R7, R8, R9 and R10 at the operatingstation 11. The collector C of the transistor 14 is connected through aresistor R15 to the base B of an NPN junction transistor 18 and thecollector C of the transistor 15 is connected connected through aresistor R16 to the base B of an NPN junction transistor 19. Similarly,the collector C of the transistor 16 is connected through a resistor R17to the base B of an NPN junction transistor and the collector C of thetransistor 17 is connected through a resistor R18 to the base B of anNPN junction transistor 21.

The collector C of the transistor 18 is connected through a load L1 to apositive potential control voltage V2 and the emitter E of thetransistor 18 is connected to ground G. The collector C of thetransistor 19 is connected through a load L2 to the voltage V2 and theemitter E of the transistor 19 is connected to ground G. Similarly, thecollector C of the transistor 20 is connected through a load L3 to thevoltage V2 and the emitter E of the transistor 20 is connected to groundG. In addition, the collector C of the transistor 21 is connectedthrough a load L4 to the voltage V2 and the emitter E of the transistor21 is connected to ground G.

The loads L1, L2, L3 and L4 are representative of control elementswithin the recording device 10 which with the flow of a control currentC1, C2, C3 an or C4 provide the various modes of operation of therecording device 10 in a manner which will be understood by thoseskilled in the art. A control current C1, C2, C3, or C4 occurs when atransistor 18, 19, 20, or 21 fires and it will be understood that theamplitude of a control current C1, C2, C3, or C4 is independent of theplurality of first voltages provided by the first voltagedivider circuit12 and the plurality of second voltages provided by the second voltagedivider circuit 13. Moreover, it will be understood that is by theselective firing of the transistors 18, 19, 20, and 21 that the controlmeans provides for control of a recording device 10. This will betterunderstood by considering the operation of the control means disclosedherein.

OPERATION In the operation of the control means disclosed herein, thefirst voltage divider circuit 12 serves as a circuit means for providinga plurality of different first voltages simultaneously to the emitters Eof the transistors 14, 15, 16, and 17 which serve as a plurality offirst potential responsive elements. Similarly, the second voltagedivider circuit 13 serves as a selecting means for selectively providinga plurality of different second voltages in sequence to the bases 13 ofthe transistors 14, 15, 16 and 17.

In connection with the plurality of difierent first voltages applied tothe transistors 14, 15, 16, and 17 by the first voltage divider circuit12, it will be understood that the voltage applied to the emitter E ofthe transistor 14 is less than the voltage V1 by the potential dropthrough the resistor R1, that the voltage applied to the emitter E ofthe transistor 15 is less than the voltage applied to the emitter E ofthe transistor 14 by the potential drop through the resistor R2, thatthe voltage applied to the emitter E of the transistor 16 is less thanthe voltage applied to the emitter E of the transistor 15 by thepotential drop through the resistor R3, and that the voltage applied tothe emitter E of the transistor 17 is less than the voltage applied tothe emitter E of the transistor 16 by the potential drop through theresistor R4. Thus, the plurality of different first voltagessimultaneously applied to the transistors 14, 15, 16, and 17 by thefirst voltage divider circuit 12 are of progressively decreasingpotential.

In that embodiment of the invention disclosed herein, the resistors R1,R2, R3, and R4 are of substantially equal value so that the potential ofthe plurality of i'ust voltages applied to the transistors 14, 15, 16,and 17 is decreased in substantially equal steps from the transistor 14to the transistor 17. Those skilled in the art will understand that eachof the transistors 14, 15, 16, and 17 will fire when the second voltageapplied to its base B by the second voltage divider circuit 13 issufficiently less than the particular first I voltage applied to itsemitter E to provide required potential difference.

It will be understood from the description of the invention above thatin applying a plurality of different second voltages to the transistors14, 15, 16 and 17, the second voltage divider circuit 13 selectivelyapplies a plurality of different second voltages in sequence to thebases B of all the transistors 14, 15, 16, and 17. Thus, whether atransistor 14, 15, 16, or 17 fires depends upon which of the pluralityof different first voltages is continuously applied to the transistor14, 15, 16, or 17 by the first voltage divider circuit 12 and upon whichof the plurality of different second voltages is selectively applied tothe transistors 14, 15, 16, or 17 by the second voltage divider circuit13.

In that embodiment of the invention disclosed herein, the resistors R11,R12, R13, and R14 are of substantially equal value and the the pluralityof diodes D serve simply to prevent a transistor 14, 15, 16, or 17 frombeing responsive to a potential applied to its base B which is greaterthan the potential applied to its emitter E. As a result, each of theplurality of second voltages which are selectively applied to thetransistors 14, 15, 16, and 17 by the second voltage divider circuit 13is substantially the same at all of the transistors 14, 15, 16, and 17.

From the foregoing, it will be understood that there is a potential ofthe point P which is such that the second voltage applied to the bases Bof the transistors 14, 15, 16, and 17 causes the transistor 14 to firebut not the transistors 15, 16, and 17. Similarly, there is another andlower potential of the point P which is such that the second voltageapplied to the bases B of the transistors 14, 15, 16 and 17 causes thetransistors 14 and 15 to both fire but not the transistors 16 and 17. Afurther lowering of the potential of the point P causes a similarselective firing of the transistors 16 and 17. Thus, the firing of thetransistors 14, 15, 16 and 17 is dependent upon the potential of thepoint P and as the potential of the point P is progressively lowered,the transistors 14, 15, 16, and 17 are progressively fired.

It is the plurality of resistors R7, R8, R9, and R10 at the operatingstation 11 which serve in the second voltage divider circuit 13 toprogressively lower the potential of the point I. From the figure, itwill be seen that a plurality of switches S1, 52,83 and S4 are providedat the operating station 11 and that upon the closing of the switch S1,the second voltage divider circuit 13 is completed to ground G from thevoltage V1 through the resistance R6 and the resistance R7. The valuesof the resistors R6 and R7 are such that the potential of the point Papplies a second voltage to the bases B of the transistors 14, 15, 16,and 17 which is sufficiently less than the first voltage applied to theemitter E of the transistor 14 to provide a potential difference thattires the transistor 14 but which is not sufiiciently less than thefirst voltages applied to the emitters E of the transistors l5, l6, andE7 to provide a potential difference that fire any of the transistorsl5, l6, and 17. Thus, the closing of a switch Sli causes the selectivefiring of only the transistor 14.

The opening of the switch S1 and the closing of the switch S2 replacesthe resistor R7 with the resistor Rd so as to lower the potential of thepoint P. The value of the resistor R8 is selected in conventional mannerso that the amount by which the potential of the point P is lowered uponclosing of the switch S2 is sufficient to provide a second voltage atthe bases B of the transistors l4, l5, l6, and 17 which is relatedto thefirst voltages being applied to the emitters E of the transistors M, l5,l6, and 17 so that the resulting potential differences fire thetransistors id and i5 but not the transistors 16 and 17. Thus, theclosing of the switch S2 causes the selective firing of the transistors14 and T5.

The opening of the switch S2 and the closing of the switch S3 or theswitch S4 replaces the resistor R8 in the second voltage divider circuit13 with either the resistor R9 or the resistor Rlll. The valves ofresistors R9 and R10 are selected in conventional manner so that theplacing of the resistor R9 in the second voltage divider circuit 13lowers the potential of the point P by an amount which is sufficient toprovide potential differences at the transistors M, 15, 16, and 17 thatfire the transistors l4, l5, and id but not the transistor 17.Similarly, the value of the resistor R10 is selected in conventionalmanner so that the placing of the resistor R10 in the second voltagedivider circuit 13 lowers the potential of the point P by an amountwhich is sufficient to provide potential differences at the resistors M,l5, l6, and 17 that fire all of the resistors M, 15, 116, and 17. Thus,the closing of the switch S3 causes the selective firing of thetransistors 1d, 15, and 16 and the closing of the switch S4 causes theselective firing of the transistors M, 15, 16, and 17.

From the figure and the foregoing description of the invention, it will'be understood that the firing ofa transistor 14, it? or l7 causes oneof the plurality of transistors 18, 19, 20, and 21 to tire. This isbecause the firing of a transistor l4, 15, id, or l7 causes thepotential of its collector C and the voltage applied to the base B of atransistor l8, 19, 20, or 21 to be reduced. I

The resistors l5, 116, 1'7, and 18 are selected so that the voltageapplied to the base B of a transistor l8, 19, 20, or 21 from thecollector C of a transistor l4, l5, 16, or 17 when a transistor M, l5,16, or 17 fires is appropriate to provide the potential differencenecessary to fire a transistor l8, 19, 20, or 211. Thus, it will beunderstood that the operation of a switch Sll, S2, S3 or S4 to provideone of a plurality of different potentials at the point P serves tocause the selective firing of a transistor l8, 19, 29, or 21 and theflow of a control current C1, C2, C3 or C4 through a load Ll, L2, L3 orL4.

Accordingly, it will also be understood that-each of the transistors Ml,l5, l6 and 17 is paired with a second voltage responsive element such asa transistor l8, H9, 20, or 21 as indicated in the FIG. to provide oneof a plurality of current means for providing a plurality of controlcurrents C1, C2, C3, and Cd in response to the plurality of secondvoltages pro vided by the second voltage divider circuit 13. It is byproviding the plurality of second voltages in response to the operationof the switches Sl, S2, S3 and S4 that the second voltage dividercircuit 13 serves as a selecting means not only for selectivelyproviding one of the plurality of second voltages but also for selectinga plurality of control currents Cl, C2, C3, and Cd and a mode ofoperation of the recording device it in connection with the controlcurrentsCl, C2, C3, an C4,

it should be emphasized that although that embodiment of the' inventiondisclosed herein provides four control currents, the number of controlcurrentsprovided by the invention is easily varied by varying the numberof transistors l4, l5, l6, and t7 and the number of transistors id, 119,20, and 21.

From the foregoing description of the operation of the control meansdisclosed herein, it will be seen that the control means is a controlmeans for controlling the operation of a recording device 10 in whichall of the control currents C1, C2, C3 and C4 are restricted to therecording device 10 and in which only a single wire for the secondvoltage divider circuit 13 is required between the recording device 10and the operating station 11. However, it should be understood that thefirst voltage divider circuit 12 is generally extended from therecording device 10 to the operating station lll as indicated by dashedline 30 in the FIG. so a ground G at the recording station 10 and aground G at'the operating station 11 are replaced by a common potentialwith only the addition of a second wire between the recording station 10and the operating station 11. This provides for more reliable control ofthe potential of the point P and of other voltages in the control meanswhile still providing a control means having only a minimum numberofwires between the recording device 10 and an operating stationll.

In addition, it should be understood that regardless of number of wires,the values selected for the resistors such as resistor R6 aresufficiently large for there to be substantially no current flow betweenthe recording station 10 and an operating station 11. Moreover, it 'willalso be understood by those skilled in the art that many variations maybe made in the embodiments chosen for the purpose of illustrating thepresent invention without departing from the scope thereof as defined bythe appended claims.

We claim:

1. In a control means for controlling from a remote operating stationthe operation of a recording device having a plurality of modes ofoperation in response to a plurality of control currents; circuit meansfor simultaneously providing at said recording device a plurality offirst voltages which differ from each other in potential; selectingmeans for sequentially providing at said recording device a plurality ofsecond voltages which differ from each other in potential, each of saidplurality of second voltages having a potential which corresponds to theresistance of one of a plurality of resistors which are of differentresistances and which are located at said remote operating station andeach of said plurality of second voltages being in response to theoperation of one of a plurality of switches which are located at saidremote operating station and which are constructed and arranged to makesaid plurality of resistors selectively operative to provide saidplurality of second voltages; and a plurality of current means forproviding a plurality of control currents restricted to said recordingdevice when operative, one of said current means being operativelyresponsive to a potential difference between another of said pluralityof first voltages and another of said plurality of second voltages.

2. The control means of claim 1 in which each of said plurality ofsecond voltages is of substantially the same potential at all of saidplurality of current means.

3. The control means of claim 2 in which said circuit means applies saidplurality of first voltages simultaneously to all of said plurality ofcurrent means.

4. The control means of claim 3 in which said selecting means appliesone of said plurality of second voltages simultaneously to all of saidplurality of current means.

5. The control means of claim 4 in which each of said plurality ofcontrol currents has an amplitude which is independent of the amplitudesof said plurality of first voltages and said plurality of secondvoltages.

6. The control means of claim 1 in which each of said plurality ofcurrent means includes a first potential responsive element forproviding an output potential in response toa potential differencebetween one of said plurality of first voltages and one of saidplurality of a second voltages, and a second potential responsiveelement for continuously providing one of said pluralitypf controlcurrents in response to said output potential.

7. The control means of claim 1 in which said selecting means includes asecond circuit means which selectively includes one of said plurality ofresistors and one of said plurality of switches and which operativelyconnects said plurality of resistors to said recording device.

8. The control means of claim 1 in which each of said current meansincludes a first switching means for providing a voltage output inresponse to a potential difference and a second switching means forproviding a control current in response to said voltage output.

9. The control means of claim 8 in which said said first switching meansis a first transistor having a collector, an

emitter to which one of said plurality of first voltages is applied, anda base to which all of said plurality of second voltages are applied insequence; and in which said second switching means is a secondtransistor having a base operatively connected to said collector of saidfirst transistor.

10. The control means of claim 9 in which said circuit means includes avoltage divider circuit.

11. The control means of claim 10 in which said selecting means includesa voltage divider circuit which selectively includes said plurality ofresistors.

1. In a control means for controlling from a remote operating stationthe operation of a recording device having a plurality of modes ofoperation in response to a plurality of control currents; circuit meansfor simultaneously providing at said recording device a plurality offirst voltages which differ from each other in potential; selectingmeans for sequentially providing at said recording device a plurality ofsecond voltages which differ from each other in potential, each of saidplurality of second voltages having a potential which corresponds to theresistance of one of a plurality of resistors which are of differentresistances and which are located at said remote operating station andeach of said plurality of second voltages being in response to theoperation of one of a plurality of switches which are located at saidremote operating station and which are constructed and arranged to makesaid plurality of resistors selectively operative to provide saidplurality of second voltages; and a plurality of current means forproviding a plurality of control currents restricted to said recordingdevice when operative, one of said current means being operativelyresponsive to a potential difference between another of said pluralityof first voltages and another of said plurality of second voltages. 2.The control means of claim 1 in which each of said plurality of secondvoltages is of substantially the same potential at all of said pluralityof current means.
 3. The control means of claim 2 in which said circuitmeans applies said plurality of first voltages simultaneously to all ofsaid plurality of current means.
 4. The control means of claim 3 inwhich said selecting means applies one of said plurality of secondvoltages simultaneously to all of said plurality of current means. 5.The control means of claim 4 in which each of said plurality of controlcurrents has an amplitude which is independent of the amplitudes of saidplurality of first voltages and said plurality of second voltages. 6.The control means of claim 1 in which each of said plurality of currentmeans includes a first potential responsive element for providing anoutput potential in response to a potential difference between one ofsaid plurality of first voltages and one of said plurality of a secondvoltages, and a second potential responsive element for continuouslyproviding one of said plurality of control currents in response to saidoutput potential.
 7. The control means of claim 1 in which saidselecting means includes a second circuit means which selectivelyincludes one of said plurality of resistors and one of said plurality ofswitches and which operatively connects said plurality of resistors tosaid recording device.
 8. The control means of claim 1 in which each ofsaid current means includes a first switching means for providing avoltage output in response to a potential difference and a secondswitching means for providing a control current in response to saidvoltage output.
 9. The control means of claim 8 in which said said firstswitching means is a first transistor having a collector, an emitter towhich one of said plurality of first voltages is applied, anD a base towhich all of said plurality of second voltages are applied in sequence;and in which said second switching means is a second transistor having abase operatively connected to said collector of said first transistor.10. The control means of claim 9 in which said circuit means includes avoltage divider circuit.
 11. The control means of claim 10 in which saidselecting means includes a voltage divider circuit which selectivelyincludes said plurality of resistors.